Directed self-assembly (DSA), which combines self-assembling materials and a lithographically defined prepattern on a photomask, is a potential candidate to extend optical lithography. A lithographically-defined guiding pattern serves to direct the self-assembly process and the pattern formed by the self-assembling materials. The resolution enhancement and self-healing effects of DSA are particularly useful for extending the resolution of optical lithography and to rectify the ill-defined patterns printed by optical lithography. To take full advantage of DSA for extending optical lithography requires modeling of the guiding pattern to be used in the photomask. Current models and methods produce guiding patterns that often cause the number and locations of DSA domains to vary from the specified number and/or locations. Accordingly, there exists a need in the art to mitigate the deficiencies and limitations described hereinabove.